JP2731825B2 - Acceleration sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of generating pressure in a flexible hydrostatic pressure transmitting material such as a steel ball moving by the action of pressure and transmitting the pressure to a sensor chip. The present invention relates to an acceleration sensor having a structure to perform.

[0002]

2. Description of the Related Art Conventionally, a three-dimensional acceleration sensor has a structure in which three one-dimensional acceleration sensors are mounted in three directions on a block such as a cube or a structure in which three elements for detecting three-dimensional acceleration are arranged on the same substrate surface. Has been proposed. Examples of this type of acceleration sensor include those disclosed in JP-A-63-118667 and JP-A-62-118260.

[0003]

The conventional multidimensional acceleration sensor has many components constituting the entire sensor system and requires complicated adjustment. Also, because of the large shape, miniaturization was also difficult. Further, the component parts are required to have high processing accuracy, and the number of parts is large, so that the assemblability is deteriorated, which is a factor of increasing the cost of the sensor. An object of the present invention is to provide an acceleration sensor that has a small number of components, is easy to assemble and adjust, and is not easily broken.

[0004]

In order to achieve the above object, an acceleration sensor according to the present invention has a silicon semiconductor substrate having a diaphragm on which a gauge film showing a resistance change due to pressure displacement is formed, and is opposed to the diaphragm. A sensor body including a pressure transmitting portion having an opening and a support cylinder connected to the pressure transmitting portion; and a flexible hydrostatic pressure filled in the pressure transmission portion and the support cylinder to transmit pressure to the diaphragm. The pressure transmission characteristic material and the pressure transmission characteristic material in the support cylinder are held in a non-contact state with the support cylinder, and when the acceleration is applied, the pressure transmission characteristic moves in the support cylinder and the pressure transmission characteristic is pushed by the pressure transmission characteristic. A pressure responsive element for applying pressure , wherein the hydrostatic pressure transmission characteristic material is
It is composed of

[0005]

When the acceleration is generated in a direction coinciding with the axis of the support cylinder, the pressure responsive body moves in the cylinder axis direction and presses the hydrostatic pressure transmission characteristic material. When the pressure responsive body moves in the direction of the pressure transmitting portion, the pressure generated in the pressure transmitting characteristic material is transmitted to the diaphragm of the sensor chip. At this time, the diaphragm is displaced in accordance with the pressure, and the displacement causes a resistance change corresponding to the pressure value in the gauge film 12 in accordance with the acceleration. This is extracted as an electric signal . Hydrostatic pressure
Silicon gel is used as the transfer characteristic material,
By using the functional capability, the sealed
Since no equipment is required, the configuration can be simplified
In both cases, there is no restriction on the mounting orientation, so the assemblability is improved.
You.

[0006]

An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a three-dimensional acceleration sensor 10 according to an embodiment of the present invention.
Is shown. The three-dimensional acceleration sensor 10 includes a sensor chip 1 made of a silicon semiconductor substrate manufactured by a semiconductor manufacturing technique and a sensor body 2 transmitting pressure to the sensor chip 1. The sensor chip 1 includes a plurality of, for example, three sensor chips 1a, 1b, and 1c formed on the same silicon wafer. As shown in FIG. 2, each of the sensor chips 1a, 1b, and 1c has a diaphragm 11 that is displaced by excitation, and a gauge film 12 that shows a resistance change due to pressure displacement is provided at a stress generating portion of the diaphragm. A hybrid integrated circuit (HI) provided with a processing circuit such as an amplifier circuit
C) An electrode pattern (not shown) such as wires for bonding wires 21 and bonding pads is provided on the substrate 20. The HIC board 20 is provided with a signal processing circuit such as an amplifier circuit. The HIC board 20 processes an electric signal obtained from a resistance change of the gauge 12 electrically bridge-connected according to the pressure applied to the diaphragm 12, and converts the sensor signal into a signal. Output.

The sensor body 2 is provided therein with pressure transmitting portions 2A, 2B, 2C for transmitting pressure to the sensor chip 1, and supporting cylinder portions 3A, 3B, 3C communicating with the pressure transmitting portions. One surface of the sensor chip 2 is superposed on the sensor chip 1, and the pressure transmitting portions 2 </ b> A, 2 </ b> B for transmitting pressure independently to the diaphragm of each sensor chip 1 are formed on the superposed surface.
2C openings 2a, 2b, 2c are provided. A steel ball 4 (hereinafter, referred to as a “G ball”) as a pressure responsive member that moves upon receiving an acceleration is disposed in each of the support cylinder portions 3A, 3B, and 3C. The sensor body 2 is made of metal, glass or resin, but is preferably made by resin molding.

As shown in FIG. 1B, the pressure transmitting section 2A
It communicates with a straight first support cylinder 3A on which the G ball 4 is provided, and the opening 3a of the first support cylinder 3A is provided coaxially with the opening 2a. Then, as shown in FIG. 1C, the pressure transmitting portions 2B and 2C have the openings 3 in a direction orthogonal to a line passing through the centers of the openings 2b and 2c.
The second and third supporting cylinder portions 3B and 3C are connected to elbow-shaped second and third supporting cylinder portions 3B and 3C having b and 3c. Second support cylinder 3
B and the third support cylinder 3C have their openings 3b and 3c in orthogonal planes to sense pressure in 900 different directions.
c is provided. Therefore, when the sensor body 2 is formed as a rectangular parallelepiped as shown in the figure, the opening 3a is formed on the surface opposite to the overlapping surface with the sensor chip 1, the opening 3b is formed on one surface perpendicular to the overlapping surface, and It is constituted by supporting cylinders 3A, 3B, 3C having openings 3c on the other surface perpendicular to both of the overlapping surfaces. If the three-dimensional acceleration sensor is installed in the state shown in FIG. 1B, silicon from the opening 3a and 3c
A lid 7 is provided to prevent the gel from falling . In particular, silicone gel has a self-shape retention function
Therefore, it is not always necessary to bind in a closed container.
No. When placed in an open space as shown in FIG. 1C,
Silicon gel does not leak even if the mounting posture is changed.
No.

In this embodiment, silicon gel is used as the hydrostatic pressure transmission characteristic material having flexibility, but a low hardness rubber-based elastic material can be used as another material. A spacer 5 is interposed between the sensor chip 1 and the sensor body 2, and the spacer 5 has windows 5a, 5b, 5 surrounding the sensor chips 1a, 1b, 1c independently.
c is provided. The spacer 5 is made of a material for assisting the bonding or joining between the sensor chip 1 and the sensor body 2,
For example, rubber is selected. The assembling of the acceleration sensor is performed by bonding the sensor chip 1 and the sensor body 2 with the spacer 5 interposed therebetween, and then opening the window 5 of the spacer 5 through the openings 3a, 3b, 3c.
a, 5b, 5c and the pressure transmitting parts 2A, 2B, 2C are filled with the silicon gel 6, and the G balls 4 are put into the silicon gel injected into the support cylinders 3A, 3B, 3C.

In the above configuration, when the acceleration is generated in the direction coinciding with the axis of the support cylinder, the G in the support cylinder is changed.
The ball 4 moves in the direction of the arrow shown in FIGS. 1B and 1C. In the movement of the G ball 4, when the G ball 4 moves in the direction of the pressure transmitting portion, the silicon gel 6 is pushed. At this time, pressure is generated in the silicon gel 6, and this pressure is transmitted to the silicon gel in the spacer to be dispersed, and transmitted to the diaphragm of the sensor chip. The diaphragm is displaced in accordance with the pressure, and the displacement causes a change in resistance of the gauge film 12 corresponding to the pressure value in accordance with the acceleration, which is extracted as an electric signal. According to the present embodiment, the movement of the G ball can be limited to only each axial direction by independently providing the support cylinders in the three axial directions, so that it is hardly affected by the acceleration applied to the other axial directions. .

Next, another embodiment of the present invention will be described. FIG.
Shows a partial cross section of an acceleration sensor in which the sensor body has a tube structure. A tube 30 serving as a sensor body is attached to the upper surface of the sensor chip 1 attached to the HIC substrate with an adhesive 22 by adhesion. The tube 2 is provided on the sensor chip 1 side. The tube 2 is provided with a pressure transmitting portion 32 and a support cylinder portion 33 for accommodating the G ball 4 communicating with the pressure transmitting portion 32. The pressure transmission part 32 is a support cylinder part 33
A pressure transmission front portion 32a having a width smaller than that of the support cylindrical portion communicating with the front end portion, ie, a width smaller than the diameter of the G ball 4; It is constituted by. The tube may be bent at a right angle to form an elbow shape, and one opening side may be configured as the same pressure transmitting portion as described above, and the other opening side may be configured as a G-ball support cylinder. In this case, the straight type and the elbow type tubes are arranged in combination in three axial directions such that each sensor chip senses acceleration in a different direction.

In this embodiment, since the pressure transmitting and expanding portion 32b is provided on the side of the pressure transmitting portion facing the sensor chip, the pressure generated by the silicon gel in the pressure transmitting front portion 32a by the G ball is reduced by the pressure. The pressure is dispersed by the transmission expanding portion 32b, and pressure can be uniformly applied to the entire diaphragm 11 of the sensor chip 1. 3 and 4 show another embodiment of the G ball. FIG. 3 shows a G ball having a disk and a tube structure. The G ball 40 includes a disk 41 to be put into the silicon gel 6 and a guide shaft 42 extending from the center of the disk. On the other hand, the tube 50 is narrowed so that the guide shaft 40 of the G ball 40 passes through the upper opening in a loosely fitted state. FIG. 4 shows a G ball having a bowl and a tube structure. The G ball 400 is composed of a bowl 410 which is covered with the silicone gel 6 and is placed in the silicone gel, and a guide shaft 420 extending from the bottom of the bowl. Bowl 4
10 is assembled in a state where the inside thereof is filled with silicon gel.

According to this embodiment, the G ball can apply a pressing force evenly over the entire width of the silicon gel in the diaphragm direction of the sensor chip, so that the acceleration sensitivity can be increased. By changing the shape of the G ball in this manner, the acceleration sensitivity can be changed. In this embodiment, the present invention is applied to a three-dimensional acceleration sensor. However, a one-dimensional or two-dimensional acceleration sensor can be configured by combining one or two sensor chips.

[0014]

As described above, according to the present invention, the pressure responsive body is held by the flexible hydrostatic pressure transmission characteristic material filled in the sensor body, and the pressure corresponding to the movement of the pressure responsive body is reduced. Since it is made to act on the diaphragm, the acceleration sensitivity can be easily changed by changing the shape of the pressure responsive body, and the acceleration sensor is protected because the entire diaphragm is sealed by the pressure transmission characteristic material. . Silicon is used as a material for hydrostatic pressure transmission.
Use of open containers is possible by using gel
The structure can be simplified, and the mounting position is restricted.
Since there is no assembly, assemblability is improved.

[Brief description of the drawings]

FIG. 1A is a perspective view showing an overall configuration of a three-dimensional acceleration sensor as an embodiment of a pressure sensor according to the present invention. FIG. 1B is a perspective view showing a general configuration of the sensor. Sectional view showing the configuration of a sensor having a supporting cylindrical portion to
FIG. 1C is a cross-sectional view showing a configuration of a sensor having a support cylinder portion that accommodates a G ball disposed at right angles to the pressure transmitting portion.

FIG. 2 is a configuration diagram showing a partial cross section of a pressure sensor according to another embodiment of the present invention.

FIG. 3 is a sectional view showing another embodiment of the G ball.

FIG. 4 is a sectional view showing another embodiment of the G ball.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sensor chip (silicon semiconductor substrate) 2 Sensor body 2A, 2B, 2C Pressure transmission part 3A, 3B, 3C Support cylinder part 4, 40, 400 G ball (pressure responder) 5 Spacer 6 Silicon gel (hydrostatic pressure transmission) Characteristic material) 7 Lid 10 3D acceleration sensor 11 Diaphragm 12 Gauge film 20 HIC substrate 30, 50 tube

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Yukio Iwasaki No. 1 Noida, Toyota, Oguchi-machi, Oguchi-machi, Niwa-gun, Aichi Prefecture Inside Tokai Rika Electric Machinery Works, Ltd. No. 1 No. 1 in Tokai Rika Electric Works, Ltd. (72) Inventor Koichi Itoigawa No. 1 No. 1 in Toyoda, Oguchi-machi, Oguchi-machi, Niwa-gun, Aichi Prefecture In-house No. 1 Tokai Rika Electric Works, Ltd. (56) References JP-A-63-75568 (JP, A) JP-A-1-197766 (JP, A) JP-A-4-20867 (JP, A) JP-A-4-1465 (JP, U) JP-A-1-118367 (JP, U) Table 3-501886 (JP, A)

Claims (1)

(57) [Claims] 1. A silicon semiconductor substrate having a diaphragm on which a gauge film exhibiting a resistance change due to a pressure displacement is formed, a pressure transmitting portion having an opening for applying pressure to the diaphragm, and a support cylinder connected to the pressure transmitting portion. A sensor body composed of a portion, a flexible hydrostatic pressure transmission material that is filled in the pressure transmission portion and the support cylinder portion and transmits pressure to the diaphragm, and the pressure transmission characteristic material in the support cylinder portion. The support tube is held in a non-contact state,
A pressure responsive element that moves within the support cylinder when acceleration is applied, and applies a pressing force to the pressure transmission characteristic material;
The hydrostatic pressure transmission characteristic material is made of silicon gel
An acceleration sensor characterized by being performed .